\f,6t  i /(//>■<■  * 


U.  S.  DEPARTMENT   OF  AGRICULTURE, 

BUREAU  OF  ENTOMOLOGY— BULLETIN  No.  116,  Part  IV. 

L.  O.  HOWARD,  Entomologist  and  Chief  of  Bureau. 


PAPERS  ON  DECIDUOUS  FRUIT  INSECTS 
AND  INSECTICIDES. 


LIME-SULPHUR  AS  A  STOMACH  POISON 

FOR  INSECTS. 


BY 


E.  W.  SCOTT  and  E.  H.  STEGLER, 

Entomological  Assistants,  Deciduous  Fruit  Insect  Investigations. 


Issued  January  17,  1913. 


°?^rW  / 


WASHINGTON: 

GOVERNMENT   PRINTING  OFFICE. 

1913. 


BUREAU  OF  ENTOMOLOGY. 

L.  O.  Howard,  Entomologist  and  ChieJ  oj  Bureau. 

C.  L.  Marlatt,  Entomologist  and  Acting  ChieJ  in  Absence  oj  Chief. 

R.  S.  Clifton,  Executive  Assistant. 

W.  F.  Tastet,  Chief  Clerk. 

F.  H.  Chittenden,  in  charge  oj  truck  crop  and  stored  product  insect  investigations. 

A.  D.  Hopkins,  in  charge  ojjorest  insect  investigations. 

W.  D.  Hunter,  in  charge  oj  southern  jield  crop  insect  investigations. 

F.  M.  Webster,  in  charge  oj  cereal  andjorage  insect  investigations. 

A.  L.  Quaintance,  in  charge  oj  deciduous  jruit  insect  investigations. 

E.  F.  Phillips,  in  charge  oj  bee  culture. 

D.  M.  Rogers,  in  charge  oj  preventing  spread  oj  moths,  jield  work. 

Rolla  P.  Currie,  in  charge  oj  editorial  work. 

Mabel  Colcord,  in  charge  oj  library. 

Deciduous  Fruit  Insect  Investigations. 
A.  L.  Quaintance,  in  charge. 

Fred  Johnson,  F.  E.  Brooks,  A.  G.  Hammar,  E.  W.  Scott,  R.  L.  Nougaret, 
R.  A.  Cushman,  L.  L.  Scott,  J.  B.  Gill,  A.  0.  Baker,  W.  M.  Davidson,  E.  B. 
Blakeslee,  W.  B.  Wood,  E.  H.  Siegler,  F.  L.  Simanton,  entomological  assistants. 

3,  F.  Zimmer,  W.  S.  Abbott,  W.  H.  Sill,  entomological  assistants,  employed  in  enforce- 
ment oj  insecticide  act,  1910. 
H 


CONTEXTS. 


Page. 

Introduction 81 

Conditions  of  the  experiments 81 

Results '. .        83 

Miscellaneous  tests 89 

Conclusions 90 


ILLUSTRATION'S. 


PLATES. 

Page. 

Pr^TE  XI.  Fig.  1.— Sprayed  twig  of  wild  cherry  showing  larvae  of  the  fall 

webworm  (Hyphantria  cunea)  feeding  on  leaves;  at  right,  same,  covered  with 

paper  bag,  to  prevent  escape  of  larvae.     Fig.  2. — Unsprayed  twig  of  wild 

cherry  upon  which  fall  webworms  have  been  feeding  for  some  time;  for 

comparison  with  sprayed  twig 84 

in 


82  DECIDUOUS    FRUIT    INSECTS    AND    INSECTICIDES. 

was  rather  resistant  against  the  burning  effect  of  the  spray  materials. 
Twigs  bearing  from  20  to  30  leaves  were  employed. 

The  spray  was  applied  to  the  foliage  by  means  of  a  large  atomizer 
of  the  type  in  which  quart  jars  are  used  as  a  container  for  the  liquid. 
The  twigs  were  sprayed  until  the  leaves  began  to  drip,  approaching 
as  nearly  as  possible  the  conditions  of  field  spraying  operations. 
Each  sprayed  twig  was  then  placed  in  a  jelly  glass  of  water,  the 
stem  extending  through  a  hole  punched  in  the  tin  cover.  (See  Plate 
XI,  figs.  1,  2.) 

After  the  spray  had  thoroughly  dried,  allowing  from  6  to  12  hours, 
20  insects  were  placed  on  the  leaves  of  each  twig.  A  large  paper 
bag  was  then  placed  over  the  twig  and  held  to  the  glass  by  means  of  a 
rubber  band.     (See  Plate  XI,  fig.  1,  at  right.) 

Observations  were  usually  made  every  other  day;  hi  some  cases 
every  day.  At  each  examination  the  bag  was  removed  and  the  dead 
larva?  taken  out  and  counted.  When  all  the  insects  were  dead,  or 
had  pupated,  as  the  case  might  be,  the  amount  of  foliage  consumed 
was  measured  in  square  inches.  A  sheet  of  celluloid  cross-sectioned 
to  one  one-hundredth  of  a  square  inch  was  utilized  for  this  purpose. 
These  measurements  were  easily  taken,  where  effective  poisons 
were  used,  as  the  young  larvae  died  before  very  much  foliage  had 
been  consumed.  The  younger  larvae  ate  only  one  surface  of  the  leaf, 
but  as  they  increased  in  size  the  leaves  were  often  skeletonized. 
Owing  to  this  fact  it  became  necessary  to  differentiate  between  the 
one  and  two  surface  feedings.  Therefore,  in  order  to  equalize  these 
conditions,  the  measurements  of  the  one  surface  feeding  were  divided 
by  two.  Another  difficulty  in  securing  feeding  measurements  in  the 
case  of  unsprayed  twigs  used  as  checks  was  encountered  when  the 
entire  leaf,  except  the  midrib  and  larger  veins,  was  consumed.  In 
such  instances  the  outline  of  the  leaf  was  nearly  obliterated,  thus 
rendering  actual  measurements  in  the  ordinary  way  impossible. 
However,  since  the  leaves  of  the  wild  cherry  selected  for  the  experi- 
ments were  fairly  uniform  in  size,  this  difficulty  was  overcome  by 
taking  the  measurement  of  an  average-size  leaf  and  substituting  it 
for  the  leaf  the  outline  of  which  had  been  destroyed.  This  method 
gave  approximately  accurate  results.  Careful  attention  was  given 
to  the  condition  of  the  foliage  throughout  the  experiments  so  as  to 
supply  the  larva?  with  palatable  food  at  all  times.  It  was  seldom 
necessary,  however,  to  renew  the  foliage,  except  for  the  unsprayed 
lots,  which  were  quickly  devoured. 

Commercial  lime-sulphur  testing  33°  Baume  was  used  at  strengths 
varying  from  J-50  to  6-50. '  In  lots  4  and  5  of  Table  VI  home- 
boiled  lime-sulphur  testing  30°  Baume  was  used  at  the  rate  of  H-50. 

1  All  the  strengths  indicated  as  above  signify  a  given  quantity  of  poison  diluted  with  water  to  make  a 
total  of  50  gallons  of  spray  material.  For  example,  lime-sulphur,  1J-50,  means  H  gallons  concentrated 
lime-sulphur  solution  diluted  with  water  to  make  50  gallons  of  spray  material.  Arsenate  of  lead,  2-50, 
means  2  pounds  arsenate  of  lead  diluted  with  water  to  make  50  gallons  of  spray  material. 


LIME-SULPHUR    A   STOMACH    POISON    FOR   INSECTS. 


83 


Arsenate  of  lead  at  strengths  varying  from  J-50  to  5-50  was  used 
in  comparison  with  the  lime-sulphur  solution.  Arsenate  of  lead  and 
lime-sulphur  were  also  used  together  at  various  strengths  (Tables 
I  and  IV).  In  the  case  of  the  arsenate  of  lead  and  the  lime- 
sulphur  most  of  the  feeding  was  done  during  the  first  three  or  four 
days.  However,  in  no  instance  was  there  much  feeding  during  the 
first  24  hours,  as  the  larvae  were  more  or  less  unsettled  until  they 
found  a  suitable  place  for  their  web.  This  was  true  on  the  unsprayed 
as  well  as  the  sprayed  leaves. 

It  will  be  found  in  the  following  pages  that  the  rate  of  killing  is 

fairly  uniform  in  all  experiments.     Since,  however,  the  tests  were 

conducted  throughout  the  season  under  different  climatic  conditions, 

slight  variations  exist. 

RESULTS. 

Experiment  I. 

The  results  given  in  Table  I  are  taken  from  an  experiment  to  obtain 
data  on  the  killing  effect  on  the  fall  webworm  of  various  chemicals 
combined  with  lime-sulphur.  Lot  1  was  the  unsprayed  check;  lot  2 
was  sprayed  with  lime-sulphur  alone  at  the  strength  of  H-50,  and 
lot  3  with  lime-sulphur,  H-50,  in  combination  with  arsenate  of  lead, 
2-50.  In  the  course  of  a  few  days  it  was  observed  that  several  larvae 
on  the  lot  sprayed  with  lime-sulphur  were  dying.  The  20  larvae  of  this 
lot  were  dead  at  the  end  of  13  days,  as  against  7  days  required  to  kill 
all  the  larva?  with  the  combination  of  arsenate  of  lead  and  lime-sul- 
phur. On  the  unsprayed  lot,  at  the  end  of  72  days,  4  larvae  were 
recorded  dead,  12  had  pupated,  and  4  were  missing. 

Table  I.— Tests  of  the  killing  effect  on  the  fall  webworm  of  lime-sulphur  alone  and  com- 
bined with  arsenate  of  lead. 


[Exper 

ment  starl 

ed  July  20 

1912,  Benton  Harbor,  Mich.,  20  larvae  in  each  lot.] 

Larvae  dying  in  each  lot. 

Date  of  examina- 
tion. 

Larvae  dying  in  each  lot. 

Date  of  examina- 
tion. 

Lotl— 
Check 
(un- 
sprayed). 

Lot  2— 
Lime- 
sulphur. 
l|-50. 

Lot  3— 
Lime- 
sulphur, 
l|-50, 

and 
arsenate 
of  lead, 

2-50. 

Lotl— 
Check 
(un- 
sprayed). 

Lot  2— 
Lime- 
sulphur, 
l*-50. 

Lot  3— 
Lime- 
sulphur. 
11-50, 
and 
arsenate 
of  lead, 
2-50. 

July   22 1 

Aug.  12 

y    23 

14 

r 

24 

1 
7 
10 
2 

16 

25 ! 

18 

26 

4 

3 
3 
4 

21 



27 

23 

28 1 

Sept.    2 

1 
2 

29 

19 

30 

30... 

31 

4 

Total  number 

dead 

Number  of  days  re- 



Aug.     1 

4 

20 

13 

0.73 

2 

2 

20 

3 

4 

- 

6 

Square    inches    of 
foliage  consumed . 

243.  20 

9 

0  12 

84 


DECID      (US  ]  BUTT    INSECTS    AND    INSECTICIDES. 


Experiment  II. 

In  order  to  obtain  further  data  on  the  killing  effect  of  lime-sulphur 
another  experiment  was  started  July  30,  using  different  strengths  of 
lime-sulphur  as  given  in  Table  II. 

Table  II. —  Tests  of  the  killing  effect  of  lime-sulphur  on  the  fall  uebuorm. 
[Experiment  started  July  30,  1912.  Benton  Harbor,  Mich.;  20  larva?  in  each  lot.] 


Larva?  dying  in  each  lot. 

Date  of 
examination. 

Larva?  dying  in  each  lot. 

Date  of 
examination. 

Lot      Lot      Lot 
1-       2-       3- 
Check  Lime-  Lime- 
• 
phur.  phur. 
| 

Lot 

Lime- 
sul- 
phur. 
6-50. 

Lot 
5  l — 
Arse- 
nate 

of 
lead, 
2-50. 

Lot 

1— 
Check  Lime- 

(un- 
sprav-  phur. 

ed)*.    : 

Lot 
3—       4— 
Lime-  Lime- 
sul-  |  sul- 
phur, phur. 

Lot 
5i— 
Arse- 
nate 

of 
lead. 

Aug.    1 

A 

. 

15 

3 

4 



1            3 

1 



1 

29 

6 

3    



1            14 

Total  num- 
ber dead.  . 
Number  days  re- 



7 

1 

1 
3 

2 
- 
4 

l 

20         20           20 





1.-. 

.... 
10 

12           9            9 

11 

1    

Square  inches  foli- 
age consumed . . . 

12 

13 . .  .    . 

1 

40.00      1.21     0.65 

•nate  of  lead  was  used  in  lot  5  for  comparison  with  the  lime-sulphur  solution. 

In  this  experiment  15  days  were  required  by  lime-sulphur.  H— 50, 
to  kill  the  20  larva?,  as  against  9  days  required  by  arsenate  of  lead, 
2-50.  Twelve  days  were  required  by  lime-sulphur,  3-50.  while  lime- 
sulphur,  6-50,  killed  the  20  larva?  in  the  same  length  of  time  required 
by  arsenate  of  lead,  2-50.  The  check  lot  was  discontinued  at  the 
end  of  30  days,  when  1  larva  was  recorded  dead  and  -40  square  inches 
of  foliage  consumed.  It  was  found  in  this  test  that  the  number  of 
square  inches  of  foliage  consumed  decreased  about  one-half  as  the 
strength  of  the  lime-sulphur  was  doubled,  the  largest  amount  being 
1.21  square  inches.  The  amount  consumed  on  the  arsenate-of-lead 
lot  was  0.83  "i  a  square  inch. 

Experiment  III. 

In  Table  III  are  shown  the  comparative  results  of  a  dosage  test 
consisting  of  seven  different  strengths  of  lime-sulphur  varying  from 
and  four  different  strengths  of  arsenate  of  lead  varying 
from  4-50  to  5-50. 


Bui.  1 1  6,  Part  IV,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agricultur 


Plate  XL 


U_    UJ 

H  .< 


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0  E 

to 

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Digitized  by  the  Internet  Archive 

in  2012  with  funding  from 

University  of  Florida,  George  A.  Smathers  Libraries  with  support  from  LYRASIS  and  the  Sloan  Foundation 


http://archive.org/details/deuouOOunit 


LIME-SULPHUR   A    STOMACH    POISON    FOR    INSECTS. 


85 


Table  III. — Tests  of  the  hilling  effect  on  the/all  webworm  of  lime-sulphur  in  comparison 

with  arsenate  of  lead. 

[Experiment  started  August  S.  1912,  Benton  Harbor,  Mich.,  20  larva?  in  each  lot.] 


Larvfe  dying 

in  each  lot. 

Date  of  examination. 

Lotl-    ^ot 

<B5r|Ef 

Lot 
3— 
Lime- 
sul- 
phur. 
1-50. 

Lot 
4— 
Lime- 
sul- 
phur. 
li-50. 

Lot 
5— 
Lime- 
sul- 
phur. 
2-50. 

Lot 
6— 

Lime- 
sul- 
phur. 
3-50. 

Lot  -:  Lot 
7-    j    8- 
Lime-  Lime- 
sul-      sul- 
phur, phur. 
5-50.    6-50. 

Lot      Lot      Lot 
9—      10—     11— 
Arse-  Arse-  Arse- 
nate   nate    nate 
of        of        of 
lead,    lead,   lead, 
§-50.    1-50.    2-50. 

Lot 
12— 
Arse- 
nate 
of 
lead, 
5-50. 

\.Ucr  io                           ...         

2  !        8 
2         11 

4 

12     -  -  - 

1           3 

15 

H 

i 

2 

8 

4 
8 
8 

5           2 
13           ('» 

2 

3 
6 

11           1 
G           4          11 

10 
2 

4 

1 

1 

Is                             

11           7    3 

80 

4 

4 

1 

ti 

2 

Sept.  2 

10 

3                

Oct.  19 

2 

Total  number  dead. 
Number  davs  required  to 

kill 

Square  inches  of  foliage 

consumed 

7         20 

14 

119.  Oi 

20 

10 

0.36 

20 
10 

0.17 

20 

12 

1.01 

20 

0.81 

20         20 

10           S 

0.  73  '  0.  2G 

20 
14 

-     3 

20 

10 

1.9S 

20 
6 

0.11 

20 
6 

0.10 

It  will  be  noted  that  lime-sulphur,  J-50,  killed  the  20  larvae  in  14 
days,  the  same  length  of  time  required  by  arsenate  of  lead,  ^-50. 
Also  lime-sulphur,  1-50,  killed  the  larva?  in  the  same  length  of  time 
as  arsenate  of  lead  1-50,  the  time  required  being  10  days.  However, 
in  both  instances  the  arsenate  of  lead  killed  more  rapidly  in  the 
beginning  than  the  lime-sulphur.  Eight  days  were  required  by 
lime-sulphur,  6-50,  to  kill  the  20  larvae  as  against  6  days  required  by 
arsenate  of  lead,  5-50.  The  amount  of  feeding  varied  somewhat  in 
this  experiment,  the  largest  amount  on  the  sprayed  lots  being  3.92 
square  inches  where  lime-sulphur,  £-50  was  used,  and  the  smallest 
amount  being  0.10  of  a  square  inch  in  lot  12  which  was  sprayed  with 
arsenate  of  lead,  5-50. 

Experiment  IV. 

The  object  of  experiment  IV  was  to  obtain  data  on  the  relation  of 
the  killing  effect  of  arsenate  of  lead  alone  and  combined  with  lime- 
sulphur,  and  to  obtain,  if  possible,  data  on  the  effect  the  addition  of 
one  to  the  other  has  upon  the  rapidity  of  killing.  Lime-sulphur 
alone  was  used  at  four  different  strengths,  and  also  was  combined  at 
the  same  rates  with  arsenate  of  lead,  2-50.  The  lime-sulphur 
strengths  employed  were  i~50,  J- 50,  1^-50,  and  3-50.  Arsenate  of 
lead,  alone,  was  tried  out  at  strengths  of  ^—50,  1-50,  2-50,  3-50,  and 
5-50,  and  also  at  the  same  strengths  was  combined  with  lime-sulphur, 
H-50.     The  results  are  given  in  Table  IV. 


S() 


DECIDTol'S    FRUIT    INSECTS    AND    INSECTICIDES. 


Table  I\'. — Tests  of  the  hilling  effect  on  the  fall  webworm  of  lime-sulphur  and  arsenate 

of  lead,  alone  and  combined. 

[Experiment  started  Aug.  L9,  1912,  Benton  Harbor,  Mich.,  20  larvae  in  each  lot.] 


Larva?  dying  in  each  lot. 

Date  of  examina- 
tion. 

Lot  I— 

Check 

(un- 

sprayed). 

Lot  2— 
Lime- 
sul- 
phur, 
■-50. 

Lot  3— 

Lime- 
sul- 
phur, 
f-50. 

Lot  4— 
Lime- 
sul- 
phur, 
li-50. 

Lot  5— 
Lime- 
sul- 
phur. 
3-50. 

Lot  6— 
Arse- 
nate of 
lead, 
£-50. 

Lot  7— 
Arse- 
nate of 
lead, 
1-50. 

Lot  8— 
Arse- 
nate of 
lead, 
2-50. 

Lot  9— 
Arse- 
nate of 
I  ead, 
3-50. 

Lot  10— 
Arse- 
nate of 
lead, 
5-50. 

Aug.  21 

1 
2 

2 

8 
10 

3 
2 
9 
6 

2* 

8 

7 
3 

3 

10 
7 

4 
2 
14 

5 
13 

2 

12 

23 

1 

25 

2              1 

s               7 
8               7 

27 

29 

31 

1               2 

Sept.    2 , j 



4 '■ I-. L 



H 



8 

10 



15 3 



Oct.     3 

5 

Total    num- 
ber dead. . . 
Number    days   re- 

8 

20 

12 

3.51 

20 
12 

2.87 

, 

S 
0.17 

20             20 
8 

20 

6 

0.36 

20 

6 

0.57 

20 
6 

0.24 

20 
4 

Square    inches    of  I 
foliage  consumed .  J      72. 00 

0.49 

2.44 

0.02 

Larva*  dying  in  each  lot. 

Lot  11— 

Lot  12— 

Lot  13— 

Lot  14— 

Lot  15— 

Lot  16— 

Lot  17— 

Lot  18— 

Date  of  examination. 

Lime- 

Lime- 

Lime- 

Lime- 

Arsenate 

Arsenate 

Arsenate 

Arsenate 

sulphur, 

sulphur, 

sulphur, 

sulphur. 

of  lead, 

of  lead, 

of  lead, 

of  lead, 

1H0; 

1J-50; 

lJ-50; 

IJ-50; 

2-50; 

2-50; 

2-50; 

2-50; 

arsenate 

arsenate 

arsenate 

arsenate 

lime- 

lime- 

lime- 

lime- 

of  lead, 

of  lead, 

of  lead, 

of  lead, 

sulphur, 

sulphur, 

sulphur, 

sulphur, 

£-50. 

1-50. 

2-50. 

5-50. 

i-50. 

|-50. 

1^-50. 

3-50. 

Aug.  21 

3 

10 

9 

5 

1 

6 

23 

2 

8 

14 
4 

9 

7 

10 

9 
2 

11 
4 

6 
13 

9 

25 

5 

27 

ti 
4 

2 

1 

29 

31.   . 

Sept.    2 



4 

:;;::;;::;;; 

r, 

8 

10                            

15 

Oct.     :5 

! 

Total    number 

dead 

20 

20 

20 

20 

20 

20 

20 

20 

Number      davs     re- 

quired to  kill 

10 

8 

8 

4 

6 

6 

6 

6 

Square  inches  of  foli- 

age consumed 

0.52 

0.02 

0.28 

0.07 

0.30 

0.19 

0.06 

0.22 

None  of  the  larvae  on  the  unsprayed  lot  died  until  September  15, 
27  days  after  the  experiment  was  started.  On  October  3  the  records 
of  this  lot  showed  8  dead,  6  pupated,  and  6  missing.  Lime-sulphur 
alone,  }-50,  and  likewise  }-50,  killed  all  the  larvae  in  12  days,  while 
the  time  required  by  strengths  of  1 §-50  and  3-50  was  8  days  in  each 
case,  the  rapidity  of  killing  being  somewhat  greater  with  the  latter 
strength.  Arsenate  of  lead  alone,  \-50,  killed  the  20  larvae  in  10  days, 
or  2  days  more  than  was  required  by  lime-sulphur,  1J-50.     Arsenate 


LIME-SULPHUR   A    STOMACH    POISON    FOR   INSECTS. 


87 


of  lead,  1-50,  2-50,  and  3-50,  each  killed  the  larvae  2  days  sooner  than 
that  required  by  lime-sulphur,  1J— 50.  Lime-sulphur,  1J-50,  when 
added  to  the  various  strengths  of  arsenate  of  lead  did  not  appreciably 
affect  the  rate  of  killing  of  the  arsenate  of  lead.  The  amount  of  feed- 
ing was  reduced  in  all  cases,  excepting  that  of  the  strongest  solution, 
lot  14,  by  the  addition  of  lime-sulphur. 

On  the  lots  sprayed  with  lime-sulphur,  i-50,  |-50,  1J-50,  and  3-50, 
combined  with  arsenate  of  lead,  2-50,  there  was  no  difference  in  the 
length  of  time  required  to  kill  the  larvae,  6  days  being  required  in  all 
cases.  The  same  number  of  days  was  required  by  arsenate  of  lead 
alone,  2-50,  but  the  rapidity  of  killing  was  somewhat  increased  by  the 
addition  of  lime-sulphur. 

Experiment  V. 

In  an  experiment  to  obtain  data  on  the  sticking  qualities  of  various 
sprays,  three  lots  of  the  regular  orchard  demonstration  strength  of 
lime-sulphur,  1  J— 50,  were  used.  The  three  lots  were  thoroughly 
sprayed  and  allowed  to  dry.  One  lot  was  then  washed  for  15  minutes 
under  a  shower  bath,  by  placing  the  twig  just  above  the  floor  in  an 
inclined  position,  allowing  the  water  to  fall  upon  it.  Another  lot  was 
washed  30  minutes  in  the  same  manner,  while  the  third  lot  remained 
unwashed. 

The  same  procedure  was  carried  out  on  three  lots  of  arsenate  of 
lead,  2-50.  After  the  twigs  were  again  thoroughly  dry  20  larvae  were 
placed  on  each.  The  results  of  this  experiment  are  to  be  found  in 
Table  V. 


Table  V. —  Tests  of  the  killing  effect  of  lime-sulphur  in  comparison  with  arsenate  of  lead 

ajter  washing  oj  each. 


[Experiment  started 

August  4 

1912,  Benton  Harbor,  Mich.,  20  larvae  in  each  lot.] 

Larvse  dying  in  each  lot. 

Date  of  examination. 

Lotl— 
Check 
(un- 

sprayed). 

Lot  2— 
Lime- 
sulphur, 
1J-50; 
not 
washed. 

Lot  3— 
Lime- 
sulphur, 

l§-50; 
washed  15 
minutes. 

Lot  4— 

Lime- 
sulphur, 

1^-50; 
washed  30 
minutes. 

Lot  5— 
Arsenate 
of  lead, 
2-50; 
not 
washed. 

Lot  6— 
Arsenate 
of  lead, 
2-50; 
washed  15 
minutes. 

Lot  7— 
Arsenate 

of  lead, 

2-50; 

washed  30 

minutes. 

1 
7 
12 

9 

2 
4 
5 
9 

11 

2 
2 
12 
4 

1 

2 
8 
9 

13 

2 
9 
7 
2 

1 

15... 

0 

17... 

1 

7 
4 

19 

21 

4 

29 

2 
3 

1 

Sept.    9 

19 

" 

Total  number  of  dead 

Number  of  days  required  to  kill . 

7 

20 
13 

0.S2 

20 
15 

1.56 

20 
13 

0.84 

20 
0.38 

20 
11 

1.79 

*  18 
17 

Square  inches  of  foliage   con- 
sumed   

111.00 

5  00 

i  2  escaped. 


88 


DECIDUOUS    FRUIT    INSECTS    AND    INSECTICIDES. 


The  washing  made  practically  no  difference  in  the  killing  effect  of 
the  lime-sulphur  spray,  the  time  of  killing  varying  from  13  to  15  days, 
and  the  amount  of  foliage  consumed  varying  from  0.82  to  1.56  square 
inches.  In  the  case  of  arsenate  of  lead,  however,  the  killing  effect  was 
considerably  retarded,  The  length  of  time  required  to  kill  all  the 
larvae  when  the  foliage  was  unwashed  was  7  days;  when  washed  15 
minutes,  11  days;  when  washed  30  minutes,  17  days.  The  amount 
of  feeding  was  0.38,  1.79,  and  5  square  inches,  respectively. 

Experiment  VI. 

To  compare  the  killing  effect  of  commercial  lime-sulphur  and  home- 
boiled  lime-sulphur,  an  experiment  was  conducted  in  which  two  lots 
of  each  kind  were  used  at  the  strength  of  1J— 50.  The  commercial 
products  tested  33°  Baume  and  the  home-boiled  30°  Baume.  The 
results  are  shown  in  Table  VI. 

Table  VI. — Tests  of  the  killing  effect  on  the  fall  webworm  of  lime-sulphur,  commercial 

and  home-boiled. 

[Experiment  started  Aug.  27.  1912,  Benton  Harbor,  Mich.,  20  larvae  in  each  lot.) 


Larvae  dying  in  each  lot. 

Date  of  examination. 

Lot  1 

(20  larvae)— 

Check  (un- 

sp  raved). 

Lot  2 
(20  larvae)— 

Commercial 

lime-sulphur, 

1V-50. 

Lot  3 
(20  larvae)— 
Commercial 
lime-sulphur, 

H-50. 

Lot  4 
(20  larvae)— 
Home-boiled 
lime-sulphur, 

1J-50. 

Lot  5 

(20  larvae)— 

Home-boiled 

lime-sulphur, 

li-50. 

Aue.  30 

Sept.  l 

4 

1 
3 
7 
6 
3 

6 

7 
7 

4 
9 
6 
1 

5 

6 

6 

9 

9 

19 

5 

Oct.  IS 

Total  number  dead    ... 
Number  of  days  required  to  kill 
Square  inches  of  foliage  consumed . 

6                       20 

9 

116.00                     1.19 

20 

12 

1.28 

20 

12 

3.05 

20 

9 

4.38 

It  was  found  that  the  commercial  and  the  home-boiled  lime-sulphur 
killed  all  the  larvae  in  the  same  average  length  of  time.  However,  the 
rapidity  of  killing  was  slightly  greater,  and  the  amount  of  foliage 
consumed  less,  where  the  commercial  material  was  used,  due  probably 
to  the  fact  that  the  commercial  solution  was  somewhat  stronger,  which 
the  Baume  tests  would  indicate. 


Experiment  VII. 

Lime-sulphur,  1J— 50,  was  tried  out  on  a  limited  number  of  pear- 
slug  larvae  (Eriocampoides  cerasi  L.),  since  only  a  few  were  available 
for  this  test.  As  in  all  the  experiments,  the  insects  were  not  placed 
upon  the  leaves  until  the  spray  had  thoroughly  dried.  The  results 
are  shown  in  Table  VII. 


LIME-SULPHUR   A   STOMACH    POISON   FOR   INSECTS. 


89 


Table  VII.—  Tests  of  the  killing  effect  of  lime-sulphur  on  the  pear  slug  (Eriocampoides 

cerasi  L.). 

| Experiment  started  Aug.  24,  1912,  Benton  Harbor,  Mich.,  6  larva?  in  each  lot.) 


Date  of  examination. 

Larvae  dying  in  each  lot. 

Lot  1  (6 

larvae)— Check 

(unsprayed). 

Lot  2  (6 
larvae) — Lime- 
sulphur,  1^-50. 

Lot  3  (6 
larva*)— Lime- 
sulphur,  U-50. 

Aug.  25 

3 
2 
1 

'     4 
2 

26 

27...- 

28 

29 

Total  number  dead. . . 
Number  of  days  required  to 

kill 

Square  inches   of     foliage 

consumed 

0 

6 
3 

0.08 

6 

3 

0.05 

1.69 

Three  days  were  required  to  kill  all  the  larvae  on  the  sprayed  lots. 
At  the  end  of  five  days,  when  the  experiment  was  closed,  the  larvae 
on  the  unsprayed  lot  were  apparently  in  a  normal  condition. 


MISCELLANEOUS  TESTS. 

Preparations  were  made  to  conduct  a  number  of  feeding  experi- 
ments on  the  killing  effect  of  lime-sulphur  on  the  second  brood  of 
codling-moth  larvae  (Carpocapsa  pomonella  L.).  But  since  a  suffi- 
cient number  of  larvae  was  not  obtainable,  owing  to  the  small  size  of 
this  brood  appearing  in  Michigan,  no  satisfactory  tests  could  be 
made.  Neither  were  there  any  tests  with  lime-sulphur  alone  made 
against  this  insect  in  the  field.  However,  in  the  case  of  a  plat  of 
Ben  Davis  apples,  sprayed  three  times  with  lime-sulphur,  1-50,  and 
10  per  cent  kerosene  emulsion,  no  arsenical  being  used,  the  total 
percentage  of  windfalls  and  picked  fruit  free  from  the  codling  moth 
was  90.18,  as  against  41.31  per  cent  of  fruit  free  from  this  insect  on 
the  unsprayed  plat.  Lime-sulphur,  1-50,  and  fish-oil  soap,  7  pounds 
to  50,  without  an  arsenical,  in  the  same  orchard  held  the  codling 
moth  to  88.19  per;  cent  of  sound  fruit.  The  effectiveness  of  lime- 
sulphur  alone  in  controlling  the  codling  moth  and  numerous  other 
insects  will  be  further  tested  during  the  season  of  1913. 

A  few  laboratory  tests  were  made  of  the  killing  effect  of  Bordeaux 
mixture,  3-4-50,  on  the  fall  webworm  and  about  as  effective  results 
were  obtained  as  from  lime-sulphur  solutions. 

Self-boiled  lime-sulphur,  8-8-50,  the  preparation  used  for  spraying 
peaches  in  foliage,  was  tried  against  the  fall  webworm  without  any 
killing  effect.  Sulphur  alone,  8-50,  and  lime  alone,  8-50,  likewise 
were  ineffective. 


90  DECIDUOUS    FRUIT    INSECTS    AND    INSECTICIDES. 

CONCLUSIONS. 

The  foregoing  tests  of  lime-sulphur  wash  against  the  larvae  of  the 
fall  webworm  show  that  this  preparation  has  decided  value  as  a 
stomach  poison.  It  is  considered  extremely  probable  that  cater- 
pillars of  many  species  of  insects,  and  perhaps  mandibulate  insects 
in  general,  will  be  similarly  susceptible.  As  shown  by  the  data  given, 
lime-sulphur,  1J-50,  while  slower  in  killing  effect  than  arsenate  of 
lead,  2-50,  nevertheless  compares  favorably  with  this  strength  of 
arsenical.  A  comparison,  however,  of  leaf-areas  eaten  by  larvae 
subjected  to  lime-sulphur  and  arsenate  of  lead,  respectively,  shows 
that  the  lime-sulphur,  especially  at  increased  strengths,  compares 
quite  favorably  with  the  arsenical  in  reducing  feeding  by  the  cater- 
pillars. 

This  action  of  lime-sulphur  as  a  stomach  poison  probably  accounts 
for  the  reported  practical  control  of  the  codling  moth  in  orchards 
treated  with  lime-sulphur  alone,  and  furnishes  an  additional  reason 
for  its  employment  as  a  fungicide. 

Experiments  in  progress  by  the  Bureau  of  Entomology  during  the 
past  two  years  warrant  the  statement  that  entirely  satisfactory 
results  in  controlling  the  codling  moth  in  orchards  may  be  obtained 
with  lime-sulphur  wash  combined  with  reduced  strengths  of  arsenate 
of  lead. 


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